1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1991, 1992 Linus Torvalds
7 * 'tty_io.c' gives an orthogonal feeling to tty's, be they consoles
8 * or rs-channels. It also implements echoing, cooked mode etc.
10 * Kill-line thanks to John T Kohl, who also corrected VMIN = VTIME = 0.
12 * Modified by Theodore Ts'o, 9/14/92, to dynamically allocate the
13 * tty_struct and tty_queue structures. Previously there was an array
14 * of 256 tty_struct's which was statically allocated, and the
15 * tty_queue structures were allocated at boot time. Both are now
16 * dynamically allocated only when the tty is open.
18 * Also restructured routines so that there is more of a separation
19 * between the high-level tty routines (tty_io.c and tty_ioctl.c) and
20 * the low-level tty routines (serial.c, pty.c, console.c). This
21 * makes for cleaner and more compact code. -TYT, 9/17/92
23 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
24 * which can be dynamically activated and de-activated by the line
25 * discipline handling modules (like SLIP).
27 * NOTE: pay no attention to the line discipline code (yet); its
28 * interface is still subject to change in this version...
31 * Added functionality to the OPOST tty handling. No delays, but all
32 * other bits should be there.
33 * -- Nick Holloway <alfie@dcs.warwick.ac.uk>, 27th May 1993.
35 * Rewrote canonical mode and added more termios flags.
36 * -- julian@uhunix.uhcc.hawaii.edu (J. Cowley), 13Jan94
38 * Reorganized FASYNC support so mouse code can share it.
39 * -- ctm@ardi.com, 9Sep95
41 * New TIOCLINUX variants added.
42 * -- mj@k332.feld.cvut.cz, 19-Nov-95
44 * Restrict vt switching via ioctl()
45 * -- grif@cs.ucr.edu, 5-Dec-95
47 * Move console and virtual terminal code to more appropriate files,
48 * implement CONFIG_VT and generalize console device interface.
49 * -- Marko Kohtala <Marko.Kohtala@hut.fi>, March 97
51 * Rewrote tty_init_dev and tty_release_dev to eliminate races.
52 * -- Bill Hawes <whawes@star.net>, June 97
54 * Added devfs support.
55 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 13-Jan-1998
57 * Added support for a Unix98-style ptmx device.
58 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
60 * Reduced memory usage for older ARM systems
61 * -- Russell King <rmk@arm.linux.org.uk>
63 * Move do_SAK() into process context. Less stack use in devfs functions.
64 * alloc_tty_struct() always uses kmalloc()
65 * -- Andrew Morton <andrewm@uow.edu.eu> 17Mar01
68 #include <linux/types.h>
69 #include <linux/major.h>
70 #include <linux/errno.h>
71 #include <linux/signal.h>
72 #include <linux/fcntl.h>
73 #include <linux/sched/signal.h>
74 #include <linux/sched/task.h>
75 #include <linux/interrupt.h>
76 #include <linux/tty.h>
77 #include <linux/tty_driver.h>
78 #include <linux/tty_flip.h>
79 #include <linux/devpts_fs.h>
80 #include <linux/file.h>
81 #include <linux/fdtable.h>
82 #include <linux/console.h>
83 #include <linux/timer.h>
84 #include <linux/ctype.h>
87 #include <linux/string.h>
88 #include <linux/slab.h>
89 #include <linux/poll.h>
90 #include <linux/ppp-ioctl.h>
91 #include <linux/proc_fs.h>
92 #include <linux/init.h>
93 #include <linux/module.h>
94 #include <linux/device.h>
95 #include <linux/wait.h>
96 #include <linux/bitops.h>
97 #include <linux/delay.h>
98 #include <linux/seq_file.h>
99 #include <linux/serial.h>
100 #include <linux/ratelimit.h>
101 #include <linux/compat.h>
103 #include <linux/uaccess.h>
105 #include <linux/kbd_kern.h>
106 #include <linux/vt_kern.h>
107 #include <linux/selection.h>
109 #include <linux/kmod.h>
110 #include <linux/nsproxy.h>
112 #undef TTY_DEBUG_HANGUP
113 #ifdef TTY_DEBUG_HANGUP
114 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
116 # define tty_debug_hangup(tty, f, args...) do { } while (0)
119 #define TTY_PARANOIA_CHECK 1
120 #define CHECK_TTY_COUNT 1
122 struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
123 .c_iflag = ICRNL | IXON,
124 .c_oflag = OPOST | ONLCR,
125 .c_cflag = B38400 | CS8 | CREAD | HUPCL,
126 .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
127 ECHOCTL | ECHOKE | IEXTEN,
131 /* .c_line = N_TTY, */
134 EXPORT_SYMBOL(tty_std_termios);
136 /* This list gets poked at by procfs and various bits of boot up code. This
137 could do with some rationalisation such as pulling the tty proc function
140 LIST_HEAD(tty_drivers); /* linked list of tty drivers */
142 /* Mutex to protect creating and releasing a tty */
143 DEFINE_MUTEX(tty_mutex);
145 static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *);
146 static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *);
147 ssize_t redirected_tty_write(struct file *, const char __user *,
149 static __poll_t tty_poll(struct file *, poll_table *);
150 static int tty_open(struct inode *, struct file *);
151 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
153 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
156 #define tty_compat_ioctl NULL
158 static int __tty_fasync(int fd, struct file *filp, int on);
159 static int tty_fasync(int fd, struct file *filp, int on);
160 static void release_tty(struct tty_struct *tty, int idx);
163 * free_tty_struct - free a disused tty
164 * @tty: tty struct to free
166 * Free the write buffers, tty queue and tty memory itself.
168 * Locking: none. Must be called after tty is definitely unused
171 static void free_tty_struct(struct tty_struct *tty)
173 tty_ldisc_deinit(tty);
174 put_device(tty->dev);
175 kfree(tty->write_buf);
176 tty->magic = 0xDEADDEAD;
180 static inline struct tty_struct *file_tty(struct file *file)
182 return ((struct tty_file_private *)file->private_data)->tty;
185 int tty_alloc_file(struct file *file)
187 struct tty_file_private *priv;
189 priv = kmalloc(sizeof(*priv), GFP_KERNEL);
193 file->private_data = priv;
198 /* Associate a new file with the tty structure */
199 void tty_add_file(struct tty_struct *tty, struct file *file)
201 struct tty_file_private *priv = file->private_data;
206 spin_lock(&tty->files_lock);
207 list_add(&priv->list, &tty->tty_files);
208 spin_unlock(&tty->files_lock);
212 * tty_free_file - free file->private_data
214 * This shall be used only for fail path handling when tty_add_file was not
217 void tty_free_file(struct file *file)
219 struct tty_file_private *priv = file->private_data;
221 file->private_data = NULL;
225 /* Delete file from its tty */
226 static void tty_del_file(struct file *file)
228 struct tty_file_private *priv = file->private_data;
229 struct tty_struct *tty = priv->tty;
231 spin_lock(&tty->files_lock);
232 list_del(&priv->list);
233 spin_unlock(&tty->files_lock);
238 * tty_name - return tty naming
239 * @tty: tty structure
241 * Convert a tty structure into a name. The name reflects the kernel
242 * naming policy and if udev is in use may not reflect user space
247 const char *tty_name(const struct tty_struct *tty)
249 if (!tty) /* Hmm. NULL pointer. That's fun. */
254 EXPORT_SYMBOL(tty_name);
256 const char *tty_driver_name(const struct tty_struct *tty)
258 if (!tty || !tty->driver)
260 return tty->driver->name;
263 static int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
266 #ifdef TTY_PARANOIA_CHECK
268 pr_warn("(%d:%d): %s: NULL tty\n",
269 imajor(inode), iminor(inode), routine);
272 if (tty->magic != TTY_MAGIC) {
273 pr_warn("(%d:%d): %s: bad magic number\n",
274 imajor(inode), iminor(inode), routine);
281 /* Caller must hold tty_lock */
282 static int check_tty_count(struct tty_struct *tty, const char *routine)
284 #ifdef CHECK_TTY_COUNT
286 int count = 0, kopen_count = 0;
288 spin_lock(&tty->files_lock);
289 list_for_each(p, &tty->tty_files) {
292 spin_unlock(&tty->files_lock);
293 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
294 tty->driver->subtype == PTY_TYPE_SLAVE &&
295 tty->link && tty->link->count)
297 if (tty_port_kopened(tty->port))
299 if (tty->count != (count + kopen_count)) {
300 tty_warn(tty, "%s: tty->count(%d) != (#fd's(%d) + #kopen's(%d))\n",
301 routine, tty->count, count, kopen_count);
302 return (count + kopen_count);
309 * get_tty_driver - find device of a tty
310 * @device: device identifier
311 * @index: returns the index of the tty
313 * This routine returns a tty driver structure, given a device number
314 * and also passes back the index number.
316 * Locking: caller must hold tty_mutex
319 static struct tty_driver *get_tty_driver(dev_t device, int *index)
321 struct tty_driver *p;
323 list_for_each_entry(p, &tty_drivers, tty_drivers) {
324 dev_t base = MKDEV(p->major, p->minor_start);
325 if (device < base || device >= base + p->num)
327 *index = device - base;
328 return tty_driver_kref_get(p);
334 * tty_dev_name_to_number - return dev_t for device name
335 * @name: user space name of device under /dev
336 * @number: pointer to dev_t that this function will populate
338 * This function converts device names like ttyS0 or ttyUSB1 into dev_t
339 * like (4, 64) or (188, 1). If no corresponding driver is registered then
340 * the function returns -ENODEV.
342 * Locking: this acquires tty_mutex to protect the tty_drivers list from
343 * being modified while we are traversing it, and makes sure to
344 * release it before exiting.
346 int tty_dev_name_to_number(const char *name, dev_t *number)
348 struct tty_driver *p;
350 int index, prefix_length = 0;
353 for (str = name; *str && !isdigit(*str); str++)
359 ret = kstrtoint(str, 10, &index);
363 prefix_length = str - name;
364 mutex_lock(&tty_mutex);
366 list_for_each_entry(p, &tty_drivers, tty_drivers)
367 if (prefix_length == strlen(p->name) && strncmp(name,
368 p->name, prefix_length) == 0) {
369 if (index < p->num) {
370 *number = MKDEV(p->major, p->minor_start + index);
375 /* if here then driver wasn't found */
378 mutex_unlock(&tty_mutex);
381 EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
383 #ifdef CONFIG_CONSOLE_POLL
386 * tty_find_polling_driver - find device of a polled tty
387 * @name: name string to match
388 * @line: pointer to resulting tty line nr
390 * This routine returns a tty driver structure, given a name
391 * and the condition that the tty driver is capable of polled
394 struct tty_driver *tty_find_polling_driver(char *name, int *line)
396 struct tty_driver *p, *res = NULL;
401 for (str = name; *str; str++)
402 if ((*str >= '0' && *str <= '9') || *str == ',')
408 tty_line = simple_strtoul(str, &str, 10);
410 mutex_lock(&tty_mutex);
411 /* Search through the tty devices to look for a match */
412 list_for_each_entry(p, &tty_drivers, tty_drivers) {
413 if (!len || strncmp(name, p->name, len) != 0)
421 if (tty_line >= 0 && tty_line < p->num && p->ops &&
422 p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
423 res = tty_driver_kref_get(p);
428 mutex_unlock(&tty_mutex);
432 EXPORT_SYMBOL_GPL(tty_find_polling_driver);
435 static ssize_t hung_up_tty_read(struct file *file, char __user *buf,
436 size_t count, loff_t *ppos)
441 static ssize_t hung_up_tty_write(struct file *file, const char __user *buf,
442 size_t count, loff_t *ppos)
447 /* No kernel lock held - none needed ;) */
448 static __poll_t hung_up_tty_poll(struct file *filp, poll_table *wait)
450 return EPOLLIN | EPOLLOUT | EPOLLERR | EPOLLHUP | EPOLLRDNORM | EPOLLWRNORM;
453 static long hung_up_tty_ioctl(struct file *file, unsigned int cmd,
456 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
459 static long hung_up_tty_compat_ioctl(struct file *file,
460 unsigned int cmd, unsigned long arg)
462 return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
465 static int hung_up_tty_fasync(int fd, struct file *file, int on)
470 static void tty_show_fdinfo(struct seq_file *m, struct file *file)
472 struct tty_struct *tty = file_tty(file);
474 if (tty && tty->ops && tty->ops->show_fdinfo)
475 tty->ops->show_fdinfo(tty, m);
478 static const struct file_operations tty_fops = {
483 .unlocked_ioctl = tty_ioctl,
484 .compat_ioctl = tty_compat_ioctl,
486 .release = tty_release,
487 .fasync = tty_fasync,
488 .show_fdinfo = tty_show_fdinfo,
491 static const struct file_operations console_fops = {
494 .write = redirected_tty_write,
496 .unlocked_ioctl = tty_ioctl,
497 .compat_ioctl = tty_compat_ioctl,
499 .release = tty_release,
500 .fasync = tty_fasync,
503 static const struct file_operations hung_up_tty_fops = {
505 .read = hung_up_tty_read,
506 .write = hung_up_tty_write,
507 .poll = hung_up_tty_poll,
508 .unlocked_ioctl = hung_up_tty_ioctl,
509 .compat_ioctl = hung_up_tty_compat_ioctl,
510 .release = tty_release,
511 .fasync = hung_up_tty_fasync,
514 static DEFINE_SPINLOCK(redirect_lock);
515 static struct file *redirect;
517 extern void tty_sysctl_init(void);
520 * tty_wakeup - request more data
523 * Internal and external helper for wakeups of tty. This function
524 * informs the line discipline if present that the driver is ready
525 * to receive more output data.
528 void tty_wakeup(struct tty_struct *tty)
530 struct tty_ldisc *ld;
532 if (test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) {
533 ld = tty_ldisc_ref(tty);
535 if (ld->ops->write_wakeup)
536 ld->ops->write_wakeup(tty);
540 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
543 EXPORT_SYMBOL_GPL(tty_wakeup);
546 * __tty_hangup - actual handler for hangup events
549 * This can be called by a "kworker" kernel thread. That is process
550 * synchronous but doesn't hold any locks, so we need to make sure we
551 * have the appropriate locks for what we're doing.
553 * The hangup event clears any pending redirections onto the hung up
554 * device. It ensures future writes will error and it does the needed
555 * line discipline hangup and signal delivery. The tty object itself
560 * redirect lock for undoing redirection
561 * file list lock for manipulating list of ttys
562 * tty_ldiscs_lock from called functions
563 * termios_rwsem resetting termios data
564 * tasklist_lock to walk task list for hangup event
565 * ->siglock to protect ->signal/->sighand
567 static void __tty_hangup(struct tty_struct *tty, int exit_session)
569 struct file *cons_filp = NULL;
570 struct file *filp, *f = NULL;
571 struct tty_file_private *priv;
572 int closecount = 0, n;
579 spin_lock(&redirect_lock);
580 if (redirect && file_tty(redirect) == tty) {
584 spin_unlock(&redirect_lock);
588 if (test_bit(TTY_HUPPED, &tty->flags)) {
594 * Some console devices aren't actually hung up for technical and
595 * historical reasons, which can lead to indefinite interruptible
596 * sleep in n_tty_read(). The following explicitly tells
597 * n_tty_read() to abort readers.
599 set_bit(TTY_HUPPING, &tty->flags);
601 /* inuse_filps is protected by the single tty lock,
602 this really needs to change if we want to flush the
603 workqueue with the lock held */
604 check_tty_count(tty, "tty_hangup");
606 spin_lock(&tty->files_lock);
607 /* This breaks for file handles being sent over AF_UNIX sockets ? */
608 list_for_each_entry(priv, &tty->tty_files, list) {
610 if (filp->f_op->write == redirected_tty_write)
612 if (filp->f_op->write != tty_write)
615 __tty_fasync(-1, filp, 0); /* can't block */
616 filp->f_op = &hung_up_tty_fops;
618 spin_unlock(&tty->files_lock);
620 refs = tty_signal_session_leader(tty, exit_session);
621 /* Account for the p->signal references we killed */
625 tty_ldisc_hangup(tty, cons_filp != NULL);
627 spin_lock_irq(&tty->ctrl_lock);
628 clear_bit(TTY_THROTTLED, &tty->flags);
629 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
630 put_pid(tty->session);
634 tty->ctrl_status = 0;
635 spin_unlock_irq(&tty->ctrl_lock);
638 * If one of the devices matches a console pointer, we
639 * cannot just call hangup() because that will cause
640 * tty->count and state->count to go out of sync.
641 * So we just call close() the right number of times.
645 for (n = 0; n < closecount; n++)
646 tty->ops->close(tty, cons_filp);
647 } else if (tty->ops->hangup)
648 tty->ops->hangup(tty);
650 * We don't want to have driver/ldisc interactions beyond the ones
651 * we did here. The driver layer expects no calls after ->hangup()
652 * from the ldisc side, which is now guaranteed.
654 set_bit(TTY_HUPPED, &tty->flags);
655 clear_bit(TTY_HUPPING, &tty->flags);
662 static void do_tty_hangup(struct work_struct *work)
664 struct tty_struct *tty =
665 container_of(work, struct tty_struct, hangup_work);
667 __tty_hangup(tty, 0);
671 * tty_hangup - trigger a hangup event
672 * @tty: tty to hangup
674 * A carrier loss (virtual or otherwise) has occurred on this like
675 * schedule a hangup sequence to run after this event.
678 void tty_hangup(struct tty_struct *tty)
680 tty_debug_hangup(tty, "hangup\n");
681 schedule_work(&tty->hangup_work);
684 EXPORT_SYMBOL(tty_hangup);
687 * tty_vhangup - process vhangup
688 * @tty: tty to hangup
690 * The user has asked via system call for the terminal to be hung up.
691 * We do this synchronously so that when the syscall returns the process
692 * is complete. That guarantee is necessary for security reasons.
695 void tty_vhangup(struct tty_struct *tty)
697 tty_debug_hangup(tty, "vhangup\n");
698 __tty_hangup(tty, 0);
701 EXPORT_SYMBOL(tty_vhangup);
705 * tty_vhangup_self - process vhangup for own ctty
707 * Perform a vhangup on the current controlling tty
710 void tty_vhangup_self(void)
712 struct tty_struct *tty;
714 tty = get_current_tty();
722 * tty_vhangup_session - hangup session leader exit
723 * @tty: tty to hangup
725 * The session leader is exiting and hanging up its controlling terminal.
726 * Every process in the foreground process group is signalled SIGHUP.
728 * We do this synchronously so that when the syscall returns the process
729 * is complete. That guarantee is necessary for security reasons.
732 void tty_vhangup_session(struct tty_struct *tty)
734 tty_debug_hangup(tty, "session hangup\n");
735 __tty_hangup(tty, 1);
739 * tty_hung_up_p - was tty hung up
740 * @filp: file pointer of tty
742 * Return true if the tty has been subject to a vhangup or a carrier
746 int tty_hung_up_p(struct file *filp)
748 return (filp && filp->f_op == &hung_up_tty_fops);
751 EXPORT_SYMBOL(tty_hung_up_p);
754 * stop_tty - propagate flow control
757 * Perform flow control to the driver. May be called
758 * on an already stopped device and will not re-call the driver
761 * This functionality is used by both the line disciplines for
762 * halting incoming flow and by the driver. It may therefore be
763 * called from any context, may be under the tty atomic_write_lock
770 void __stop_tty(struct tty_struct *tty)
779 void stop_tty(struct tty_struct *tty)
783 spin_lock_irqsave(&tty->flow_lock, flags);
785 spin_unlock_irqrestore(&tty->flow_lock, flags);
787 EXPORT_SYMBOL(stop_tty);
790 * start_tty - propagate flow control
793 * Start a tty that has been stopped if at all possible. If this
794 * tty was previous stopped and is now being started, the driver
795 * start method is invoked and the line discipline woken.
801 void __start_tty(struct tty_struct *tty)
803 if (!tty->stopped || tty->flow_stopped)
807 tty->ops->start(tty);
811 void start_tty(struct tty_struct *tty)
815 spin_lock_irqsave(&tty->flow_lock, flags);
817 spin_unlock_irqrestore(&tty->flow_lock, flags);
819 EXPORT_SYMBOL(start_tty);
821 static void tty_update_time(struct timespec64 *time)
823 time64_t sec = ktime_get_real_seconds();
826 * We only care if the two values differ in anything other than the
827 * lower three bits (i.e every 8 seconds). If so, then we can update
828 * the time of the tty device, otherwise it could be construded as a
829 * security leak to let userspace know the exact timing of the tty.
831 if ((sec ^ time->tv_sec) & ~7)
836 * tty_read - read method for tty device files
837 * @file: pointer to tty file
839 * @count: size of user buffer
842 * Perform the read system call function on this terminal device. Checks
843 * for hung up devices before calling the line discipline method.
846 * Locks the line discipline internally while needed. Multiple
847 * read calls may be outstanding in parallel.
850 static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
854 struct inode *inode = file_inode(file);
855 struct tty_struct *tty = file_tty(file);
856 struct tty_ldisc *ld;
858 if (tty_paranoia_check(tty, inode, "tty_read"))
860 if (!tty || tty_io_error(tty))
863 /* We want to wait for the line discipline to sort out in this
865 ld = tty_ldisc_ref_wait(tty);
867 return hung_up_tty_read(file, buf, count, ppos);
869 i = ld->ops->read(tty, file, buf, count);
875 tty_update_time(&inode->i_atime);
880 static void tty_write_unlock(struct tty_struct *tty)
882 mutex_unlock(&tty->atomic_write_lock);
883 wake_up_interruptible_poll(&tty->write_wait, EPOLLOUT);
886 static int tty_write_lock(struct tty_struct *tty, int ndelay)
888 if (!mutex_trylock(&tty->atomic_write_lock)) {
891 if (mutex_lock_interruptible(&tty->atomic_write_lock))
898 * Split writes up in sane blocksizes to avoid
899 * denial-of-service type attacks
901 static inline ssize_t do_tty_write(
902 ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
903 struct tty_struct *tty,
905 const char __user *buf,
908 ssize_t ret, written = 0;
911 ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
916 * We chunk up writes into a temporary buffer. This
917 * simplifies low-level drivers immensely, since they
918 * don't have locking issues and user mode accesses.
920 * But if TTY_NO_WRITE_SPLIT is set, we should use a
923 * The default chunk-size is 2kB, because the NTTY
924 * layer has problems with bigger chunks. It will
925 * claim to be able to handle more characters than
928 * FIXME: This can probably go away now except that 64K chunks
929 * are too likely to fail unless switched to vmalloc...
932 if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
937 /* write_buf/write_cnt is protected by the atomic_write_lock mutex */
938 if (tty->write_cnt < chunk) {
939 unsigned char *buf_chunk;
944 buf_chunk = kmalloc(chunk, GFP_KERNEL);
949 kfree(tty->write_buf);
950 tty->write_cnt = chunk;
951 tty->write_buf = buf_chunk;
954 /* Do the write .. */
960 if (copy_from_user(tty->write_buf, buf, size))
962 ret = write(tty, file, tty->write_buf, size);
971 if (signal_pending(current))
976 tty_update_time(&file_inode(file)->i_mtime);
980 tty_write_unlock(tty);
985 * tty_write_message - write a message to a certain tty, not just the console.
986 * @tty: the destination tty_struct
987 * @msg: the message to write
989 * This is used for messages that need to be redirected to a specific tty.
990 * We don't put it into the syslog queue right now maybe in the future if
993 * We must still hold the BTM and test the CLOSING flag for the moment.
996 void tty_write_message(struct tty_struct *tty, char *msg)
999 mutex_lock(&tty->atomic_write_lock);
1001 if (tty->ops->write && tty->count > 0)
1002 tty->ops->write(tty, msg, strlen(msg));
1004 tty_write_unlock(tty);
1011 * tty_write - write method for tty device file
1012 * @file: tty file pointer
1013 * @buf: user data to write
1014 * @count: bytes to write
1017 * Write data to a tty device via the line discipline.
1020 * Locks the line discipline as required
1021 * Writes to the tty driver are serialized by the atomic_write_lock
1022 * and are then processed in chunks to the device. The line discipline
1023 * write method will not be invoked in parallel for each device.
1026 static ssize_t tty_write(struct file *file, const char __user *buf,
1027 size_t count, loff_t *ppos)
1029 struct tty_struct *tty = file_tty(file);
1030 struct tty_ldisc *ld;
1033 if (tty_paranoia_check(tty, file_inode(file), "tty_write"))
1035 if (!tty || !tty->ops->write || tty_io_error(tty))
1037 /* Short term debug to catch buggy drivers */
1038 if (tty->ops->write_room == NULL)
1039 tty_err(tty, "missing write_room method\n");
1040 ld = tty_ldisc_ref_wait(tty);
1042 return hung_up_tty_write(file, buf, count, ppos);
1043 if (!ld->ops->write)
1046 ret = do_tty_write(ld->ops->write, tty, file, buf, count);
1047 tty_ldisc_deref(ld);
1051 ssize_t redirected_tty_write(struct file *file, const char __user *buf,
1052 size_t count, loff_t *ppos)
1054 struct file *p = NULL;
1056 spin_lock(&redirect_lock);
1058 p = get_file(redirect);
1059 spin_unlock(&redirect_lock);
1063 res = vfs_write(p, buf, count, &p->f_pos);
1067 return tty_write(file, buf, count, ppos);
1071 * tty_send_xchar - send priority character
1073 * Send a high priority character to the tty even if stopped
1075 * Locking: none for xchar method, write ordering for write method.
1078 int tty_send_xchar(struct tty_struct *tty, char ch)
1080 int was_stopped = tty->stopped;
1082 if (tty->ops->send_xchar) {
1083 down_read(&tty->termios_rwsem);
1084 tty->ops->send_xchar(tty, ch);
1085 up_read(&tty->termios_rwsem);
1089 if (tty_write_lock(tty, 0) < 0)
1090 return -ERESTARTSYS;
1092 down_read(&tty->termios_rwsem);
1095 tty->ops->write(tty, &ch, 1);
1098 up_read(&tty->termios_rwsem);
1099 tty_write_unlock(tty);
1103 static char ptychar[] = "pqrstuvwxyzabcde";
1106 * pty_line_name - generate name for a pty
1107 * @driver: the tty driver in use
1108 * @index: the minor number
1109 * @p: output buffer of at least 6 bytes
1111 * Generate a name from a driver reference and write it to the output
1116 static void pty_line_name(struct tty_driver *driver, int index, char *p)
1118 int i = index + driver->name_base;
1119 /* ->name is initialized to "ttyp", but "tty" is expected */
1120 sprintf(p, "%s%c%x",
1121 driver->subtype == PTY_TYPE_SLAVE ? "tty" : driver->name,
1122 ptychar[i >> 4 & 0xf], i & 0xf);
1126 * tty_line_name - generate name for a tty
1127 * @driver: the tty driver in use
1128 * @index: the minor number
1129 * @p: output buffer of at least 7 bytes
1131 * Generate a name from a driver reference and write it to the output
1136 static ssize_t tty_line_name(struct tty_driver *driver, int index, char *p)
1138 if (driver->flags & TTY_DRIVER_UNNUMBERED_NODE)
1139 return sprintf(p, "%s", driver->name);
1141 return sprintf(p, "%s%d", driver->name,
1142 index + driver->name_base);
1146 * tty_driver_lookup_tty() - find an existing tty, if any
1147 * @driver: the driver for the tty
1148 * @idx: the minor number
1150 * Return the tty, if found. If not found, return NULL or ERR_PTR() if the
1151 * driver lookup() method returns an error.
1153 * Locking: tty_mutex must be held. If the tty is found, bump the tty kref.
1155 static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
1156 struct file *file, int idx)
1158 struct tty_struct *tty;
1160 if (driver->ops->lookup)
1162 tty = ERR_PTR(-EIO);
1164 tty = driver->ops->lookup(driver, file, idx);
1166 tty = driver->ttys[idx];
1174 * tty_init_termios - helper for termios setup
1175 * @tty: the tty to set up
1177 * Initialise the termios structure for this tty. This runs under
1178 * the tty_mutex currently so we can be relaxed about ordering.
1181 void tty_init_termios(struct tty_struct *tty)
1183 struct ktermios *tp;
1184 int idx = tty->index;
1186 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1187 tty->termios = tty->driver->init_termios;
1189 /* Check for lazy saved data */
1190 tp = tty->driver->termios[idx];
1193 tty->termios.c_line = tty->driver->init_termios.c_line;
1195 tty->termios = tty->driver->init_termios;
1197 /* Compatibility until drivers always set this */
1198 tty->termios.c_ispeed = tty_termios_input_baud_rate(&tty->termios);
1199 tty->termios.c_ospeed = tty_termios_baud_rate(&tty->termios);
1201 EXPORT_SYMBOL_GPL(tty_init_termios);
1203 int tty_standard_install(struct tty_driver *driver, struct tty_struct *tty)
1205 tty_init_termios(tty);
1206 tty_driver_kref_get(driver);
1208 driver->ttys[tty->index] = tty;
1211 EXPORT_SYMBOL_GPL(tty_standard_install);
1214 * tty_driver_install_tty() - install a tty entry in the driver
1215 * @driver: the driver for the tty
1218 * Install a tty object into the driver tables. The tty->index field
1219 * will be set by the time this is called. This method is responsible
1220 * for ensuring any need additional structures are allocated and
1223 * Locking: tty_mutex for now
1225 static int tty_driver_install_tty(struct tty_driver *driver,
1226 struct tty_struct *tty)
1228 return driver->ops->install ? driver->ops->install(driver, tty) :
1229 tty_standard_install(driver, tty);
1233 * tty_driver_remove_tty() - remove a tty from the driver tables
1234 * @driver: the driver for the tty
1235 * @tty: tty to remove
1237 * Remvoe a tty object from the driver tables. The tty->index field
1238 * will be set by the time this is called.
1240 * Locking: tty_mutex for now
1242 static void tty_driver_remove_tty(struct tty_driver *driver, struct tty_struct *tty)
1244 if (driver->ops->remove)
1245 driver->ops->remove(driver, tty);
1247 driver->ttys[tty->index] = NULL;
1251 * tty_reopen() - fast re-open of an open tty
1252 * @tty: the tty to open
1254 * Return 0 on success, -errno on error.
1255 * Re-opens on master ptys are not allowed and return -EIO.
1257 * Locking: Caller must hold tty_lock
1259 static int tty_reopen(struct tty_struct *tty)
1261 struct tty_driver *driver = tty->driver;
1262 struct tty_ldisc *ld;
1265 if (driver->type == TTY_DRIVER_TYPE_PTY &&
1266 driver->subtype == PTY_TYPE_MASTER)
1272 if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
1275 ld = tty_ldisc_ref_wait(tty);
1277 tty_ldisc_deref(ld);
1279 retval = tty_ldisc_lock(tty, 5 * HZ);
1284 retval = tty_ldisc_reinit(tty, tty->termios.c_line);
1285 tty_ldisc_unlock(tty);
1295 * tty_init_dev - initialise a tty device
1296 * @driver: tty driver we are opening a device on
1297 * @idx: device index
1299 * Prepare a tty device. This may not be a "new" clean device but
1300 * could also be an active device. The pty drivers require special
1301 * handling because of this.
1304 * The function is called under the tty_mutex, which
1305 * protects us from the tty struct or driver itself going away.
1307 * On exit the tty device has the line discipline attached and
1308 * a reference count of 1. If a pair was created for pty/tty use
1309 * and the other was a pty master then it too has a reference count of 1.
1311 * WSH 06/09/97: Rewritten to remove races and properly clean up after a
1312 * failed open. The new code protects the open with a mutex, so it's
1313 * really quite straightforward. The mutex locking can probably be
1314 * relaxed for the (most common) case of reopening a tty.
1316 * Return: returned tty structure
1319 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx)
1321 struct tty_struct *tty;
1325 * First time open is complex, especially for PTY devices.
1326 * This code guarantees that either everything succeeds and the
1327 * TTY is ready for operation, or else the table slots are vacated
1328 * and the allocated memory released. (Except that the termios
1332 if (!try_module_get(driver->owner))
1333 return ERR_PTR(-ENODEV);
1335 tty = alloc_tty_struct(driver, idx);
1338 goto err_module_put;
1342 retval = tty_driver_install_tty(driver, tty);
1347 tty->port = driver->ports[idx];
1349 if (WARN_RATELIMIT(!tty->port,
1350 "%s: %s driver does not set tty->port. This would crash the kernel. Fix the driver!\n",
1351 __func__, tty->driver->name)) {
1353 goto err_release_lock;
1356 retval = tty_ldisc_lock(tty, 5 * HZ);
1358 goto err_release_lock;
1359 tty->port->itty = tty;
1362 * Structures all installed ... call the ldisc open routines.
1363 * If we fail here just call release_tty to clean up. No need
1364 * to decrement the use counts, as release_tty doesn't care.
1366 retval = tty_ldisc_setup(tty, tty->link);
1368 goto err_release_tty;
1369 tty_ldisc_unlock(tty);
1370 /* Return the tty locked so that it cannot vanish under the caller */
1375 free_tty_struct(tty);
1377 module_put(driver->owner);
1378 return ERR_PTR(retval);
1380 /* call the tty release_tty routine to clean out this slot */
1382 tty_ldisc_unlock(tty);
1383 tty_info_ratelimited(tty, "ldisc open failed (%d), clearing slot %d\n",
1387 release_tty(tty, idx);
1388 return ERR_PTR(retval);
1392 * tty_save_termios() - save tty termios data in driver table
1393 * @tty: tty whose termios data to save
1395 * Locking: Caller guarantees serialisation with tty_init_termios().
1397 void tty_save_termios(struct tty_struct *tty)
1399 struct ktermios *tp;
1400 int idx = tty->index;
1402 /* If the port is going to reset then it has no termios to save */
1403 if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS)
1406 /* Stash the termios data */
1407 tp = tty->driver->termios[idx];
1409 tp = kmalloc(sizeof(*tp), GFP_KERNEL);
1412 tty->driver->termios[idx] = tp;
1416 EXPORT_SYMBOL_GPL(tty_save_termios);
1419 * tty_flush_works - flush all works of a tty/pty pair
1420 * @tty: tty device to flush works for (or either end of a pty pair)
1422 * Sync flush all works belonging to @tty (and the 'other' tty).
1424 static void tty_flush_works(struct tty_struct *tty)
1426 flush_work(&tty->SAK_work);
1427 flush_work(&tty->hangup_work);
1429 flush_work(&tty->link->SAK_work);
1430 flush_work(&tty->link->hangup_work);
1435 * release_one_tty - release tty structure memory
1436 * @work: work of tty we are obliterating
1438 * Releases memory associated with a tty structure, and clears out the
1439 * driver table slots. This function is called when a device is no longer
1440 * in use. It also gets called when setup of a device fails.
1443 * takes the file list lock internally when working on the list
1444 * of ttys that the driver keeps.
1446 * This method gets called from a work queue so that the driver private
1447 * cleanup ops can sleep (needed for USB at least)
1449 static void release_one_tty(struct work_struct *work)
1451 struct tty_struct *tty =
1452 container_of(work, struct tty_struct, hangup_work);
1453 struct tty_driver *driver = tty->driver;
1454 struct module *owner = driver->owner;
1456 if (tty->ops->cleanup)
1457 tty->ops->cleanup(tty);
1460 tty_driver_kref_put(driver);
1463 spin_lock(&tty->files_lock);
1464 list_del_init(&tty->tty_files);
1465 spin_unlock(&tty->files_lock);
1468 put_pid(tty->session);
1469 free_tty_struct(tty);
1472 static void queue_release_one_tty(struct kref *kref)
1474 struct tty_struct *tty = container_of(kref, struct tty_struct, kref);
1476 /* The hangup queue is now free so we can reuse it rather than
1477 waste a chunk of memory for each port */
1478 INIT_WORK(&tty->hangup_work, release_one_tty);
1479 schedule_work(&tty->hangup_work);
1483 * tty_kref_put - release a tty kref
1486 * Release a reference to a tty device and if need be let the kref
1487 * layer destruct the object for us
1490 void tty_kref_put(struct tty_struct *tty)
1493 kref_put(&tty->kref, queue_release_one_tty);
1495 EXPORT_SYMBOL(tty_kref_put);
1498 * release_tty - release tty structure memory
1500 * Release both @tty and a possible linked partner (think pty pair),
1501 * and decrement the refcount of the backing module.
1505 * takes the file list lock internally when working on the list
1506 * of ttys that the driver keeps.
1509 static void release_tty(struct tty_struct *tty, int idx)
1511 /* This should always be true but check for the moment */
1512 WARN_ON(tty->index != idx);
1513 WARN_ON(!mutex_is_locked(&tty_mutex));
1514 if (tty->ops->shutdown)
1515 tty->ops->shutdown(tty);
1516 tty_save_termios(tty);
1517 tty_driver_remove_tty(tty->driver, tty);
1518 tty->port->itty = NULL;
1520 tty->link->port->itty = NULL;
1521 tty_buffer_cancel_work(tty->port);
1523 tty_buffer_cancel_work(tty->link->port);
1525 tty_kref_put(tty->link);
1530 * tty_release_checks - check a tty before real release
1531 * @tty: tty to check
1532 * @idx: index of the tty
1534 * Performs some paranoid checking before true release of the @tty.
1535 * This is a no-op unless TTY_PARANOIA_CHECK is defined.
1537 static int tty_release_checks(struct tty_struct *tty, int idx)
1539 #ifdef TTY_PARANOIA_CHECK
1540 if (idx < 0 || idx >= tty->driver->num) {
1541 tty_debug(tty, "bad idx %d\n", idx);
1545 /* not much to check for devpts */
1546 if (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)
1549 if (tty != tty->driver->ttys[idx]) {
1550 tty_debug(tty, "bad driver table[%d] = %p\n",
1551 idx, tty->driver->ttys[idx]);
1554 if (tty->driver->other) {
1555 struct tty_struct *o_tty = tty->link;
1557 if (o_tty != tty->driver->other->ttys[idx]) {
1558 tty_debug(tty, "bad other table[%d] = %p\n",
1559 idx, tty->driver->other->ttys[idx]);
1562 if (o_tty->link != tty) {
1563 tty_debug(tty, "bad link = %p\n", o_tty->link);
1572 * tty_kclose - closes tty opened by tty_kopen
1575 * Performs the final steps to release and free a tty device. It is the
1576 * same as tty_release_struct except that it also resets TTY_PORT_KOPENED
1577 * flag on tty->port.
1579 void tty_kclose(struct tty_struct *tty)
1582 * Ask the line discipline code to release its structures
1584 tty_ldisc_release(tty);
1586 /* Wait for pending work before tty destruction commmences */
1587 tty_flush_works(tty);
1589 tty_debug_hangup(tty, "freeing structure\n");
1591 * The release_tty function takes care of the details of clearing
1592 * the slots and preserving the termios structure.
1594 mutex_lock(&tty_mutex);
1595 tty_port_set_kopened(tty->port, 0);
1596 release_tty(tty, tty->index);
1597 mutex_unlock(&tty_mutex);
1599 EXPORT_SYMBOL_GPL(tty_kclose);
1602 * tty_release_struct - release a tty struct
1604 * @idx: index of the tty
1606 * Performs the final steps to release and free a tty device. It is
1607 * roughly the reverse of tty_init_dev.
1609 void tty_release_struct(struct tty_struct *tty, int idx)
1612 * Ask the line discipline code to release its structures
1614 tty_ldisc_release(tty);
1616 /* Wait for pending work before tty destruction commmences */
1617 tty_flush_works(tty);
1619 tty_debug_hangup(tty, "freeing structure\n");
1621 * The release_tty function takes care of the details of clearing
1622 * the slots and preserving the termios structure.
1624 mutex_lock(&tty_mutex);
1625 release_tty(tty, idx);
1626 mutex_unlock(&tty_mutex);
1628 EXPORT_SYMBOL_GPL(tty_release_struct);
1631 * tty_release - vfs callback for close
1632 * @inode: inode of tty
1633 * @filp: file pointer for handle to tty
1635 * Called the last time each file handle is closed that references
1636 * this tty. There may however be several such references.
1639 * Takes bkl. See tty_release_dev
1641 * Even releasing the tty structures is a tricky business.. We have
1642 * to be very careful that the structures are all released at the
1643 * same time, as interrupts might otherwise get the wrong pointers.
1645 * WSH 09/09/97: rewritten to avoid some nasty race conditions that could
1646 * lead to double frees or releasing memory still in use.
1649 int tty_release(struct inode *inode, struct file *filp)
1651 struct tty_struct *tty = file_tty(filp);
1652 struct tty_struct *o_tty = NULL;
1653 int do_sleep, final;
1658 if (tty_paranoia_check(tty, inode, __func__))
1662 check_tty_count(tty, __func__);
1664 __tty_fasync(-1, filp, 0);
1667 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
1668 tty->driver->subtype == PTY_TYPE_MASTER)
1671 if (tty_release_checks(tty, idx)) {
1676 tty_debug_hangup(tty, "releasing (count=%d)\n", tty->count);
1678 if (tty->ops->close)
1679 tty->ops->close(tty, filp);
1681 /* If tty is pty master, lock the slave pty (stable lock order) */
1682 tty_lock_slave(o_tty);
1685 * Sanity check: if tty->count is going to zero, there shouldn't be
1686 * any waiters on tty->read_wait or tty->write_wait. We test the
1687 * wait queues and kick everyone out _before_ actually starting to
1688 * close. This ensures that we won't block while releasing the tty
1691 * The test for the o_tty closing is necessary, since the master and
1692 * slave sides may close in any order. If the slave side closes out
1693 * first, its count will be one, since the master side holds an open.
1694 * Thus this test wouldn't be triggered at the time the slave closed,
1700 if (tty->count <= 1) {
1701 if (waitqueue_active(&tty->read_wait)) {
1702 wake_up_poll(&tty->read_wait, EPOLLIN);
1705 if (waitqueue_active(&tty->write_wait)) {
1706 wake_up_poll(&tty->write_wait, EPOLLOUT);
1710 if (o_tty && o_tty->count <= 1) {
1711 if (waitqueue_active(&o_tty->read_wait)) {
1712 wake_up_poll(&o_tty->read_wait, EPOLLIN);
1715 if (waitqueue_active(&o_tty->write_wait)) {
1716 wake_up_poll(&o_tty->write_wait, EPOLLOUT);
1725 tty_warn(tty, "read/write wait queue active!\n");
1727 schedule_timeout_killable(timeout);
1728 if (timeout < 120 * HZ)
1729 timeout = 2 * timeout + 1;
1731 timeout = MAX_SCHEDULE_TIMEOUT;
1735 if (--o_tty->count < 0) {
1736 tty_warn(tty, "bad slave count (%d)\n", o_tty->count);
1740 if (--tty->count < 0) {
1741 tty_warn(tty, "bad tty->count (%d)\n", tty->count);
1746 * We've decremented tty->count, so we need to remove this file
1747 * descriptor off the tty->tty_files list; this serves two
1749 * - check_tty_count sees the correct number of file descriptors
1750 * associated with this tty.
1751 * - do_tty_hangup no longer sees this file descriptor as
1752 * something that needs to be handled for hangups.
1757 * Perform some housekeeping before deciding whether to return.
1759 * If _either_ side is closing, make sure there aren't any
1760 * processes that still think tty or o_tty is their controlling
1764 read_lock(&tasklist_lock);
1765 session_clear_tty(tty->session);
1767 session_clear_tty(o_tty->session);
1768 read_unlock(&tasklist_lock);
1771 /* check whether both sides are closing ... */
1772 final = !tty->count && !(o_tty && o_tty->count);
1774 tty_unlock_slave(o_tty);
1777 /* At this point, the tty->count == 0 should ensure a dead tty
1778 cannot be re-opened by a racing opener */
1783 tty_debug_hangup(tty, "final close\n");
1785 tty_release_struct(tty, idx);
1790 * tty_open_current_tty - get locked tty of current task
1791 * @device: device number
1792 * @filp: file pointer to tty
1793 * @return: locked tty of the current task iff @device is /dev/tty
1795 * Performs a re-open of the current task's controlling tty.
1797 * We cannot return driver and index like for the other nodes because
1798 * devpts will not work then. It expects inodes to be from devpts FS.
1800 static struct tty_struct *tty_open_current_tty(dev_t device, struct file *filp)
1802 struct tty_struct *tty;
1805 if (device != MKDEV(TTYAUX_MAJOR, 0))
1808 tty = get_current_tty();
1810 return ERR_PTR(-ENXIO);
1812 filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */
1815 tty_kref_put(tty); /* safe to drop the kref now */
1817 retval = tty_reopen(tty);
1820 tty = ERR_PTR(retval);
1826 * tty_lookup_driver - lookup a tty driver for a given device file
1827 * @device: device number
1828 * @filp: file pointer to tty
1829 * @index: index for the device in the @return driver
1830 * @return: driver for this inode (with increased refcount)
1832 * If @return is not erroneous, the caller is responsible to decrement the
1833 * refcount by tty_driver_kref_put.
1835 * Locking: tty_mutex protects get_tty_driver
1837 static struct tty_driver *tty_lookup_driver(dev_t device, struct file *filp,
1840 struct tty_driver *driver = NULL;
1844 case MKDEV(TTY_MAJOR, 0): {
1845 extern struct tty_driver *console_driver;
1846 driver = tty_driver_kref_get(console_driver);
1847 *index = fg_console;
1851 case MKDEV(TTYAUX_MAJOR, 1): {
1852 struct tty_driver *console_driver = console_device(index);
1853 if (console_driver) {
1854 driver = tty_driver_kref_get(console_driver);
1855 if (driver && filp) {
1856 /* Don't let /dev/console block */
1857 filp->f_flags |= O_NONBLOCK;
1862 tty_driver_kref_put(driver);
1863 return ERR_PTR(-ENODEV);
1866 driver = get_tty_driver(device, index);
1868 return ERR_PTR(-ENODEV);
1875 * tty_kopen - open a tty device for kernel
1876 * @device: dev_t of device to open
1878 * Opens tty exclusively for kernel. Performs the driver lookup,
1879 * makes sure it's not already opened and performs the first-time
1880 * tty initialization.
1882 * Returns the locked initialized &tty_struct
1884 * Claims the global tty_mutex to serialize:
1885 * - concurrent first-time tty initialization
1886 * - concurrent tty driver removal w/ lookup
1887 * - concurrent tty removal from driver table
1889 struct tty_struct *tty_kopen(dev_t device)
1891 struct tty_struct *tty;
1892 struct tty_driver *driver;
1895 mutex_lock(&tty_mutex);
1896 driver = tty_lookup_driver(device, NULL, &index);
1897 if (IS_ERR(driver)) {
1898 mutex_unlock(&tty_mutex);
1899 return ERR_CAST(driver);
1902 /* check whether we're reopening an existing tty */
1903 tty = tty_driver_lookup_tty(driver, NULL, index);
1908 /* drop kref from tty_driver_lookup_tty() */
1910 tty = ERR_PTR(-EBUSY);
1911 } else { /* tty_init_dev returns tty with the tty_lock held */
1912 tty = tty_init_dev(driver, index);
1915 tty_port_set_kopened(tty->port, 1);
1918 mutex_unlock(&tty_mutex);
1919 tty_driver_kref_put(driver);
1922 EXPORT_SYMBOL_GPL(tty_kopen);
1925 * tty_open_by_driver - open a tty device
1926 * @device: dev_t of device to open
1927 * @filp: file pointer to tty
1929 * Performs the driver lookup, checks for a reopen, or otherwise
1930 * performs the first-time tty initialization.
1932 * Returns the locked initialized or re-opened &tty_struct
1934 * Claims the global tty_mutex to serialize:
1935 * - concurrent first-time tty initialization
1936 * - concurrent tty driver removal w/ lookup
1937 * - concurrent tty removal from driver table
1939 static struct tty_struct *tty_open_by_driver(dev_t device,
1942 struct tty_struct *tty;
1943 struct tty_driver *driver = NULL;
1947 mutex_lock(&tty_mutex);
1948 driver = tty_lookup_driver(device, filp, &index);
1949 if (IS_ERR(driver)) {
1950 mutex_unlock(&tty_mutex);
1951 return ERR_CAST(driver);
1954 /* check whether we're reopening an existing tty */
1955 tty = tty_driver_lookup_tty(driver, filp, index);
1957 mutex_unlock(&tty_mutex);
1962 if (tty_port_kopened(tty->port)) {
1964 mutex_unlock(&tty_mutex);
1965 tty = ERR_PTR(-EBUSY);
1968 mutex_unlock(&tty_mutex);
1969 retval = tty_lock_interruptible(tty);
1970 tty_kref_put(tty); /* drop kref from tty_driver_lookup_tty() */
1972 if (retval == -EINTR)
1973 retval = -ERESTARTSYS;
1974 tty = ERR_PTR(retval);
1977 retval = tty_reopen(tty);
1980 tty = ERR_PTR(retval);
1982 } else { /* Returns with the tty_lock held for now */
1983 tty = tty_init_dev(driver, index);
1984 mutex_unlock(&tty_mutex);
1987 tty_driver_kref_put(driver);
1992 * tty_open - open a tty device
1993 * @inode: inode of device file
1994 * @filp: file pointer to tty
1996 * tty_open and tty_release keep up the tty count that contains the
1997 * number of opens done on a tty. We cannot use the inode-count, as
1998 * different inodes might point to the same tty.
2000 * Open-counting is needed for pty masters, as well as for keeping
2001 * track of serial lines: DTR is dropped when the last close happens.
2002 * (This is not done solely through tty->count, now. - Ted 1/27/92)
2004 * The termios state of a pty is reset on first open so that
2005 * settings don't persist across reuse.
2007 * Locking: tty_mutex protects tty, tty_lookup_driver and tty_init_dev.
2008 * tty->count should protect the rest.
2009 * ->siglock protects ->signal/->sighand
2011 * Note: the tty_unlock/lock cases without a ref are only safe due to
2015 static int tty_open(struct inode *inode, struct file *filp)
2017 struct tty_struct *tty;
2019 dev_t device = inode->i_rdev;
2020 unsigned saved_flags = filp->f_flags;
2022 nonseekable_open(inode, filp);
2025 retval = tty_alloc_file(filp);
2029 tty = tty_open_current_tty(device, filp);
2031 tty = tty_open_by_driver(device, filp);
2034 tty_free_file(filp);
2035 retval = PTR_ERR(tty);
2036 if (retval != -EAGAIN || signal_pending(current))
2042 tty_add_file(tty, filp);
2044 check_tty_count(tty, __func__);
2045 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
2048 retval = tty->ops->open(tty, filp);
2051 filp->f_flags = saved_flags;
2054 tty_debug_hangup(tty, "open error %d, releasing\n", retval);
2056 tty_unlock(tty); /* need to call tty_release without BTM */
2057 tty_release(inode, filp);
2058 if (retval != -ERESTARTSYS)
2061 if (signal_pending(current))
2066 * Need to reset f_op in case a hangup happened.
2068 if (tty_hung_up_p(filp))
2069 filp->f_op = &tty_fops;
2072 clear_bit(TTY_HUPPED, &tty->flags);
2074 noctty = (filp->f_flags & O_NOCTTY) ||
2075 (IS_ENABLED(CONFIG_VT) && device == MKDEV(TTY_MAJOR, 0)) ||
2076 device == MKDEV(TTYAUX_MAJOR, 1) ||
2077 (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2078 tty->driver->subtype == PTY_TYPE_MASTER);
2080 tty_open_proc_set_tty(filp, tty);
2088 * tty_poll - check tty status
2089 * @filp: file being polled
2090 * @wait: poll wait structures to update
2092 * Call the line discipline polling method to obtain the poll
2093 * status of the device.
2095 * Locking: locks called line discipline but ldisc poll method
2096 * may be re-entered freely by other callers.
2099 static __poll_t tty_poll(struct file *filp, poll_table *wait)
2101 struct tty_struct *tty = file_tty(filp);
2102 struct tty_ldisc *ld;
2105 if (tty_paranoia_check(tty, file_inode(filp), "tty_poll"))
2108 ld = tty_ldisc_ref_wait(tty);
2110 return hung_up_tty_poll(filp, wait);
2112 ret = ld->ops->poll(tty, filp, wait);
2113 tty_ldisc_deref(ld);
2117 static int __tty_fasync(int fd, struct file *filp, int on)
2119 struct tty_struct *tty = file_tty(filp);
2120 unsigned long flags;
2123 if (tty_paranoia_check(tty, file_inode(filp), "tty_fasync"))
2126 retval = fasync_helper(fd, filp, on, &tty->fasync);
2134 spin_lock_irqsave(&tty->ctrl_lock, flags);
2137 type = PIDTYPE_PGID;
2139 pid = task_pid(current);
2140 type = PIDTYPE_TGID;
2143 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
2144 __f_setown(filp, pid, type, 0);
2152 static int tty_fasync(int fd, struct file *filp, int on)
2154 struct tty_struct *tty = file_tty(filp);
2155 int retval = -ENOTTY;
2158 if (!tty_hung_up_p(filp))
2159 retval = __tty_fasync(fd, filp, on);
2166 * tiocsti - fake input character
2167 * @tty: tty to fake input into
2168 * @p: pointer to character
2170 * Fake input to a tty device. Does the necessary locking and
2173 * FIXME: does not honour flow control ??
2176 * Called functions take tty_ldiscs_lock
2177 * current->signal->tty check is safe without locks
2179 * FIXME: may race normal receive processing
2182 static int tiocsti(struct tty_struct *tty, char __user *p)
2185 struct tty_ldisc *ld;
2187 if ((current->signal->tty != tty) && !capable(CAP_SYS_ADMIN))
2189 if (get_user(ch, p))
2191 tty_audit_tiocsti(tty, ch);
2192 ld = tty_ldisc_ref_wait(tty);
2195 if (ld->ops->receive_buf)
2196 ld->ops->receive_buf(tty, &ch, &mbz, 1);
2197 tty_ldisc_deref(ld);
2202 * tiocgwinsz - implement window query ioctl
2204 * @arg: user buffer for result
2206 * Copies the kernel idea of the window size into the user buffer.
2208 * Locking: tty->winsize_mutex is taken to ensure the winsize data
2212 static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
2216 mutex_lock(&tty->winsize_mutex);
2217 err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
2218 mutex_unlock(&tty->winsize_mutex);
2220 return err ? -EFAULT: 0;
2224 * tty_do_resize - resize event
2225 * @tty: tty being resized
2226 * @ws: new dimensions
2228 * Update the termios variables and send the necessary signals to
2229 * peform a terminal resize correctly
2232 int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
2237 mutex_lock(&tty->winsize_mutex);
2238 if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
2241 /* Signal the foreground process group */
2242 pgrp = tty_get_pgrp(tty);
2244 kill_pgrp(pgrp, SIGWINCH, 1);
2249 mutex_unlock(&tty->winsize_mutex);
2252 EXPORT_SYMBOL(tty_do_resize);
2255 * tiocswinsz - implement window size set ioctl
2256 * @tty: tty side of tty
2257 * @arg: user buffer for result
2259 * Copies the user idea of the window size to the kernel. Traditionally
2260 * this is just advisory information but for the Linux console it
2261 * actually has driver level meaning and triggers a VC resize.
2264 * Driver dependent. The default do_resize method takes the
2265 * tty termios mutex and ctrl_lock. The console takes its own lock
2266 * then calls into the default method.
2269 static int tiocswinsz(struct tty_struct *tty, struct winsize __user *arg)
2271 struct winsize tmp_ws;
2272 if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
2275 if (tty->ops->resize)
2276 return tty->ops->resize(tty, &tmp_ws);
2278 return tty_do_resize(tty, &tmp_ws);
2282 * tioccons - allow admin to move logical console
2283 * @file: the file to become console
2285 * Allow the administrator to move the redirected console device
2287 * Locking: uses redirect_lock to guard the redirect information
2290 static int tioccons(struct file *file)
2292 if (!capable(CAP_SYS_ADMIN))
2294 if (file->f_op->write == redirected_tty_write) {
2296 spin_lock(&redirect_lock);
2299 spin_unlock(&redirect_lock);
2304 spin_lock(&redirect_lock);
2306 spin_unlock(&redirect_lock);
2309 redirect = get_file(file);
2310 spin_unlock(&redirect_lock);
2315 * tiocsetd - set line discipline
2317 * @p: pointer to user data
2319 * Set the line discipline according to user request.
2321 * Locking: see tty_set_ldisc, this function is just a helper
2324 static int tiocsetd(struct tty_struct *tty, int __user *p)
2329 if (get_user(disc, p))
2332 ret = tty_set_ldisc(tty, disc);
2338 * tiocgetd - get line discipline
2340 * @p: pointer to user data
2342 * Retrieves the line discipline id directly from the ldisc.
2344 * Locking: waits for ldisc reference (in case the line discipline
2345 * is changing or the tty is being hungup)
2348 static int tiocgetd(struct tty_struct *tty, int __user *p)
2350 struct tty_ldisc *ld;
2353 ld = tty_ldisc_ref_wait(tty);
2356 ret = put_user(ld->ops->num, p);
2357 tty_ldisc_deref(ld);
2362 * send_break - performed time break
2363 * @tty: device to break on
2364 * @duration: timeout in mS
2366 * Perform a timed break on hardware that lacks its own driver level
2367 * timed break functionality.
2370 * atomic_write_lock serializes
2374 static int send_break(struct tty_struct *tty, unsigned int duration)
2378 if (tty->ops->break_ctl == NULL)
2381 if (tty->driver->flags & TTY_DRIVER_HARDWARE_BREAK)
2382 retval = tty->ops->break_ctl(tty, duration);
2384 /* Do the work ourselves */
2385 if (tty_write_lock(tty, 0) < 0)
2387 retval = tty->ops->break_ctl(tty, -1);
2390 if (!signal_pending(current))
2391 msleep_interruptible(duration);
2392 retval = tty->ops->break_ctl(tty, 0);
2394 tty_write_unlock(tty);
2395 if (signal_pending(current))
2402 * tty_tiocmget - get modem status
2404 * @p: pointer to result
2406 * Obtain the modem status bits from the tty driver if the feature
2407 * is supported. Return -EINVAL if it is not available.
2409 * Locking: none (up to the driver)
2412 static int tty_tiocmget(struct tty_struct *tty, int __user *p)
2414 int retval = -EINVAL;
2416 if (tty->ops->tiocmget) {
2417 retval = tty->ops->tiocmget(tty);
2420 retval = put_user(retval, p);
2426 * tty_tiocmset - set modem status
2428 * @cmd: command - clear bits, set bits or set all
2429 * @p: pointer to desired bits
2431 * Set the modem status bits from the tty driver if the feature
2432 * is supported. Return -EINVAL if it is not available.
2434 * Locking: none (up to the driver)
2437 static int tty_tiocmset(struct tty_struct *tty, unsigned int cmd,
2441 unsigned int set, clear, val;
2443 if (tty->ops->tiocmset == NULL)
2446 retval = get_user(val, p);
2462 set &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2463 clear &= TIOCM_DTR|TIOCM_RTS|TIOCM_OUT1|TIOCM_OUT2|TIOCM_LOOP;
2464 return tty->ops->tiocmset(tty, set, clear);
2467 static int tty_tiocgicount(struct tty_struct *tty, void __user *arg)
2469 int retval = -EINVAL;
2470 struct serial_icounter_struct icount;
2471 memset(&icount, 0, sizeof(icount));
2472 if (tty->ops->get_icount)
2473 retval = tty->ops->get_icount(tty, &icount);
2476 if (copy_to_user(arg, &icount, sizeof(icount)))
2481 static int tty_tiocsserial(struct tty_struct *tty, struct serial_struct __user *ss)
2483 static DEFINE_RATELIMIT_STATE(depr_flags,
2484 DEFAULT_RATELIMIT_INTERVAL,
2485 DEFAULT_RATELIMIT_BURST);
2486 char comm[TASK_COMM_LEN];
2487 struct serial_struct v;
2490 if (copy_from_user(&v, ss, sizeof(*ss)))
2493 flags = v.flags & ASYNC_DEPRECATED;
2495 if (flags && __ratelimit(&depr_flags))
2496 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2497 __func__, get_task_comm(comm, current), flags);
2498 if (!tty->ops->set_serial)
2500 return tty->ops->set_serial(tty, &v);
2503 static int tty_tiocgserial(struct tty_struct *tty, struct serial_struct __user *ss)
2505 struct serial_struct v;
2508 memset(&v, 0, sizeof(v));
2509 if (!tty->ops->get_serial)
2511 err = tty->ops->get_serial(tty, &v);
2512 if (!err && copy_to_user(ss, &v, sizeof(v)))
2518 * if pty, return the slave side (real_tty)
2519 * otherwise, return self
2521 static struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
2523 if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
2524 tty->driver->subtype == PTY_TYPE_MASTER)
2530 * Split this up, as gcc can choke on it otherwise..
2532 long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
2534 struct tty_struct *tty = file_tty(file);
2535 struct tty_struct *real_tty;
2536 void __user *p = (void __user *)arg;
2538 struct tty_ldisc *ld;
2540 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2543 real_tty = tty_pair_get_tty(tty);
2546 * Factor out some common prep work
2554 retval = tty_check_change(tty);
2557 if (cmd != TIOCCBRK) {
2558 tty_wait_until_sent(tty, 0);
2559 if (signal_pending(current))
2570 return tiocsti(tty, p);
2572 return tiocgwinsz(real_tty, p);
2574 return tiocswinsz(real_tty, p);
2576 return real_tty != tty ? -EINVAL : tioccons(file);
2578 set_bit(TTY_EXCLUSIVE, &tty->flags);
2581 clear_bit(TTY_EXCLUSIVE, &tty->flags);
2585 int excl = test_bit(TTY_EXCLUSIVE, &tty->flags);
2586 return put_user(excl, (int __user *)p);
2589 return tiocgetd(tty, p);
2591 return tiocsetd(tty, p);
2593 if (!capable(CAP_SYS_ADMIN))
2599 unsigned int ret = new_encode_dev(tty_devnum(real_tty));
2600 return put_user(ret, (unsigned int __user *)p);
2605 case TIOCSBRK: /* Turn break on, unconditionally */
2606 if (tty->ops->break_ctl)
2607 return tty->ops->break_ctl(tty, -1);
2609 case TIOCCBRK: /* Turn break off, unconditionally */
2610 if (tty->ops->break_ctl)
2611 return tty->ops->break_ctl(tty, 0);
2613 case TCSBRK: /* SVID version: non-zero arg --> no break */
2614 /* non-zero arg means wait for all output data
2615 * to be sent (performed above) but don't send break.
2616 * This is used by the tcdrain() termios function.
2619 return send_break(tty, 250);
2621 case TCSBRKP: /* support for POSIX tcsendbreak() */
2622 return send_break(tty, arg ? arg*100 : 250);
2625 return tty_tiocmget(tty, p);
2629 return tty_tiocmset(tty, cmd, p);
2631 return tty_tiocgicount(tty, p);
2636 /* flush tty buffer and allow ldisc to process ioctl */
2637 tty_buffer_flush(tty, NULL);
2642 return tty_tiocsserial(tty, p);
2644 return tty_tiocgserial(tty, p);
2646 /* Special because the struct file is needed */
2647 return ptm_open_peer(file, tty, (int)arg);
2649 retval = tty_jobctrl_ioctl(tty, real_tty, file, cmd, arg);
2650 if (retval != -ENOIOCTLCMD)
2653 if (tty->ops->ioctl) {
2654 retval = tty->ops->ioctl(tty, cmd, arg);
2655 if (retval != -ENOIOCTLCMD)
2658 ld = tty_ldisc_ref_wait(tty);
2660 return hung_up_tty_ioctl(file, cmd, arg);
2662 if (ld->ops->ioctl) {
2663 retval = ld->ops->ioctl(tty, file, cmd, arg);
2664 if (retval == -ENOIOCTLCMD)
2667 tty_ldisc_deref(ld);
2671 #ifdef CONFIG_COMPAT
2673 struct serial_struct32 {
2679 compat_int_t xmit_fifo_size;
2680 compat_int_t custom_divisor;
2681 compat_int_t baud_base;
2682 unsigned short close_delay;
2686 unsigned short closing_wait; /* time to wait before closing */
2687 unsigned short closing_wait2; /* no longer used... */
2688 compat_uint_t iomem_base;
2689 unsigned short iomem_reg_shift;
2690 unsigned int port_high;
2691 /* compat_ulong_t iomap_base FIXME */
2692 compat_int_t reserved;
2695 static int compat_tty_tiocsserial(struct tty_struct *tty,
2696 struct serial_struct32 __user *ss)
2698 static DEFINE_RATELIMIT_STATE(depr_flags,
2699 DEFAULT_RATELIMIT_INTERVAL,
2700 DEFAULT_RATELIMIT_BURST);
2701 char comm[TASK_COMM_LEN];
2702 struct serial_struct32 v32;
2703 struct serial_struct v;
2706 if (copy_from_user(&v32, ss, sizeof(*ss)))
2709 memcpy(&v, &v32, offsetof(struct serial_struct32, iomem_base));
2710 v.iomem_base = compat_ptr(v32.iomem_base);
2711 v.iomem_reg_shift = v32.iomem_reg_shift;
2712 v.port_high = v32.port_high;
2715 flags = v.flags & ASYNC_DEPRECATED;
2717 if (flags && __ratelimit(&depr_flags))
2718 pr_warn("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
2719 __func__, get_task_comm(comm, current), flags);
2720 if (!tty->ops->set_serial)
2722 return tty->ops->set_serial(tty, &v);
2725 static int compat_tty_tiocgserial(struct tty_struct *tty,
2726 struct serial_struct32 __user *ss)
2728 struct serial_struct32 v32;
2729 struct serial_struct v;
2732 memset(&v, 0, sizeof(v));
2733 memset(&v32, 0, sizeof(v32));
2735 if (!tty->ops->get_serial)
2737 err = tty->ops->get_serial(tty, &v);
2739 memcpy(&v32, &v, offsetof(struct serial_struct32, iomem_base));
2740 v32.iomem_base = (unsigned long)v.iomem_base >> 32 ?
2741 0xfffffff : ptr_to_compat(v.iomem_base);
2742 v32.iomem_reg_shift = v.iomem_reg_shift;
2743 v32.port_high = v.port_high;
2744 if (copy_to_user(ss, &v32, sizeof(v32)))
2749 static long tty_compat_ioctl(struct file *file, unsigned int cmd,
2752 struct tty_struct *tty = file_tty(file);
2753 struct tty_ldisc *ld;
2754 int retval = -ENOIOCTLCMD;
2803 case TIOCGLCKTRMIOS:
2804 case TIOCSLCKTRMIOS:
2816 return tty_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
2832 return tty_ioctl(file, cmd, arg);
2835 if (tty_paranoia_check(tty, file_inode(file), "tty_ioctl"))
2840 return compat_tty_tiocsserial(tty, compat_ptr(arg));
2842 return compat_tty_tiocgserial(tty, compat_ptr(arg));
2844 if (tty->ops->compat_ioctl) {
2845 retval = tty->ops->compat_ioctl(tty, cmd, arg);
2846 if (retval != -ENOIOCTLCMD)
2850 ld = tty_ldisc_ref_wait(tty);
2852 return hung_up_tty_compat_ioctl(file, cmd, arg);
2853 if (ld->ops->compat_ioctl)
2854 retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
2855 if (retval == -ENOIOCTLCMD && ld->ops->ioctl)
2856 retval = ld->ops->ioctl(tty, file,
2857 (unsigned long)compat_ptr(cmd), arg);
2858 tty_ldisc_deref(ld);
2864 static int this_tty(const void *t, struct file *file, unsigned fd)
2866 if (likely(file->f_op->read != tty_read))
2868 return file_tty(file) != t ? 0 : fd + 1;
2872 * This implements the "Secure Attention Key" --- the idea is to
2873 * prevent trojan horses by killing all processes associated with this
2874 * tty when the user hits the "Secure Attention Key". Required for
2875 * super-paranoid applications --- see the Orange Book for more details.
2877 * This code could be nicer; ideally it should send a HUP, wait a few
2878 * seconds, then send a INT, and then a KILL signal. But you then
2879 * have to coordinate with the init process, since all processes associated
2880 * with the current tty must be dead before the new getty is allowed
2883 * Now, if it would be correct ;-/ The current code has a nasty hole -
2884 * it doesn't catch files in flight. We may send the descriptor to ourselves
2885 * via AF_UNIX socket, close it and later fetch from socket. FIXME.
2887 * Nasty bug: do_SAK is being called in interrupt context. This can
2888 * deadlock. We punt it up to process context. AKPM - 16Mar2001
2890 void __do_SAK(struct tty_struct *tty)
2895 struct task_struct *g, *p;
2896 struct pid *session;
2901 session = tty->session;
2903 tty_ldisc_flush(tty);
2905 tty_driver_flush_buffer(tty);
2907 read_lock(&tasklist_lock);
2908 /* Kill the entire session */
2909 do_each_pid_task(session, PIDTYPE_SID, p) {
2910 tty_notice(tty, "SAK: killed process %d (%s): by session\n",
2911 task_pid_nr(p), p->comm);
2912 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2913 } while_each_pid_task(session, PIDTYPE_SID, p);
2915 /* Now kill any processes that happen to have the tty open */
2916 do_each_thread(g, p) {
2917 if (p->signal->tty == tty) {
2918 tty_notice(tty, "SAK: killed process %d (%s): by controlling tty\n",
2919 task_pid_nr(p), p->comm);
2920 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2924 i = iterate_fd(p->files, 0, this_tty, tty);
2926 tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
2927 task_pid_nr(p), p->comm, i - 1);
2928 group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_SID);
2931 } while_each_thread(g, p);
2932 read_unlock(&tasklist_lock);
2936 static void do_SAK_work(struct work_struct *work)
2938 struct tty_struct *tty =
2939 container_of(work, struct tty_struct, SAK_work);
2944 * The tq handling here is a little racy - tty->SAK_work may already be queued.
2945 * Fortunately we don't need to worry, because if ->SAK_work is already queued,
2946 * the values which we write to it will be identical to the values which it
2947 * already has. --akpm
2949 void do_SAK(struct tty_struct *tty)
2953 schedule_work(&tty->SAK_work);
2956 EXPORT_SYMBOL(do_SAK);
2958 /* Must put_device() after it's unused! */
2959 static struct device *tty_get_device(struct tty_struct *tty)
2961 dev_t devt = tty_devnum(tty);
2962 return class_find_device_by_devt(tty_class, devt);
2969 * This subroutine allocates and initializes a tty structure.
2971 * Locking: none - tty in question is not exposed at this point
2974 struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
2976 struct tty_struct *tty;
2978 tty = kzalloc(sizeof(*tty), GFP_KERNEL);
2982 kref_init(&tty->kref);
2983 tty->magic = TTY_MAGIC;
2984 if (tty_ldisc_init(tty)) {
2988 tty->session = NULL;
2990 mutex_init(&tty->legacy_mutex);
2991 mutex_init(&tty->throttle_mutex);
2992 init_rwsem(&tty->termios_rwsem);
2993 mutex_init(&tty->winsize_mutex);
2994 init_ldsem(&tty->ldisc_sem);
2995 init_waitqueue_head(&tty->write_wait);
2996 init_waitqueue_head(&tty->read_wait);
2997 INIT_WORK(&tty->hangup_work, do_tty_hangup);
2998 mutex_init(&tty->atomic_write_lock);
2999 spin_lock_init(&tty->ctrl_lock);
3000 spin_lock_init(&tty->flow_lock);
3001 spin_lock_init(&tty->files_lock);
3002 INIT_LIST_HEAD(&tty->tty_files);
3003 INIT_WORK(&tty->SAK_work, do_SAK_work);
3005 tty->driver = driver;
3006 tty->ops = driver->ops;
3008 tty_line_name(driver, idx, tty->name);
3009 tty->dev = tty_get_device(tty);
3015 * tty_put_char - write one character to a tty
3019 * Write one byte to the tty using the provided put_char method
3020 * if present. Returns the number of characters successfully output.
3022 * Note: the specific put_char operation in the driver layer may go
3023 * away soon. Don't call it directly, use this method
3026 int tty_put_char(struct tty_struct *tty, unsigned char ch)
3028 if (tty->ops->put_char)
3029 return tty->ops->put_char(tty, ch);
3030 return tty->ops->write(tty, &ch, 1);
3032 EXPORT_SYMBOL_GPL(tty_put_char);
3034 struct class *tty_class;
3036 static int tty_cdev_add(struct tty_driver *driver, dev_t dev,
3037 unsigned int index, unsigned int count)
3041 /* init here, since reused cdevs cause crashes */
3042 driver->cdevs[index] = cdev_alloc();
3043 if (!driver->cdevs[index])
3045 driver->cdevs[index]->ops = &tty_fops;
3046 driver->cdevs[index]->owner = driver->owner;
3047 err = cdev_add(driver->cdevs[index], dev, count);
3049 kobject_put(&driver->cdevs[index]->kobj);
3054 * tty_register_device - register a tty device
3055 * @driver: the tty driver that describes the tty device
3056 * @index: the index in the tty driver for this tty device
3057 * @device: a struct device that is associated with this tty device.
3058 * This field is optional, if there is no known struct device
3059 * for this tty device it can be set to NULL safely.
3061 * Returns a pointer to the struct device for this tty device
3062 * (or ERR_PTR(-EFOO) on error).
3064 * This call is required to be made to register an individual tty device
3065 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3066 * that bit is not set, this function should not be called by a tty
3072 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
3073 struct device *device)
3075 return tty_register_device_attr(driver, index, device, NULL, NULL);
3077 EXPORT_SYMBOL(tty_register_device);
3079 static void tty_device_create_release(struct device *dev)
3081 dev_dbg(dev, "releasing...\n");
3086 * tty_register_device_attr - register a tty device
3087 * @driver: the tty driver that describes the tty device
3088 * @index: the index in the tty driver for this tty device
3089 * @device: a struct device that is associated with this tty device.
3090 * This field is optional, if there is no known struct device
3091 * for this tty device it can be set to NULL safely.
3092 * @drvdata: Driver data to be set to device.
3093 * @attr_grp: Attribute group to be set on device.
3095 * Returns a pointer to the struct device for this tty device
3096 * (or ERR_PTR(-EFOO) on error).
3098 * This call is required to be made to register an individual tty device
3099 * if the tty driver's flags have the TTY_DRIVER_DYNAMIC_DEV bit set. If
3100 * that bit is not set, this function should not be called by a tty
3105 struct device *tty_register_device_attr(struct tty_driver *driver,
3106 unsigned index, struct device *device,
3108 const struct attribute_group **attr_grp)
3111 dev_t devt = MKDEV(driver->major, driver->minor_start) + index;
3112 struct ktermios *tp;
3116 if (index >= driver->num) {
3117 pr_err("%s: Attempt to register invalid tty line number (%d)\n",
3118 driver->name, index);
3119 return ERR_PTR(-EINVAL);
3122 if (driver->type == TTY_DRIVER_TYPE_PTY)
3123 pty_line_name(driver, index, name);
3125 tty_line_name(driver, index, name);
3127 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3129 return ERR_PTR(-ENOMEM);
3132 dev->class = tty_class;
3133 dev->parent = device;
3134 dev->release = tty_device_create_release;
3135 dev_set_name(dev, "%s", name);
3136 dev->groups = attr_grp;
3137 dev_set_drvdata(dev, drvdata);
3139 dev_set_uevent_suppress(dev, 1);
3141 retval = device_register(dev);
3145 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3147 * Free any saved termios data so that the termios state is
3148 * reset when reusing a minor number.
3150 tp = driver->termios[index];
3152 driver->termios[index] = NULL;
3156 retval = tty_cdev_add(driver, devt, index, 1);
3161 dev_set_uevent_suppress(dev, 0);
3162 kobject_uevent(&dev->kobj, KOBJ_ADD);
3171 return ERR_PTR(retval);
3173 EXPORT_SYMBOL_GPL(tty_register_device_attr);
3176 * tty_unregister_device - unregister a tty device
3177 * @driver: the tty driver that describes the tty device
3178 * @index: the index in the tty driver for this tty device
3180 * If a tty device is registered with a call to tty_register_device() then
3181 * this function must be called when the tty device is gone.
3186 void tty_unregister_device(struct tty_driver *driver, unsigned index)
3188 device_destroy(tty_class,
3189 MKDEV(driver->major, driver->minor_start) + index);
3190 if (!(driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3191 cdev_del(driver->cdevs[index]);
3192 driver->cdevs[index] = NULL;
3195 EXPORT_SYMBOL(tty_unregister_device);
3198 * __tty_alloc_driver -- allocate tty driver
3199 * @lines: count of lines this driver can handle at most
3200 * @owner: module which is responsible for this driver
3201 * @flags: some of TTY_DRIVER_* flags, will be set in driver->flags
3203 * This should not be called directly, some of the provided macros should be
3204 * used instead. Use IS_ERR and friends on @retval.
3206 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
3207 unsigned long flags)
3209 struct tty_driver *driver;
3210 unsigned int cdevs = 1;
3213 if (!lines || (flags & TTY_DRIVER_UNNUMBERED_NODE && lines > 1))
3214 return ERR_PTR(-EINVAL);
3216 driver = kzalloc(sizeof(*driver), GFP_KERNEL);
3218 return ERR_PTR(-ENOMEM);
3220 kref_init(&driver->kref);
3221 driver->magic = TTY_DRIVER_MAGIC;
3222 driver->num = lines;
3223 driver->owner = owner;
3224 driver->flags = flags;
3226 if (!(flags & TTY_DRIVER_DEVPTS_MEM)) {
3227 driver->ttys = kcalloc(lines, sizeof(*driver->ttys),
3229 driver->termios = kcalloc(lines, sizeof(*driver->termios),
3231 if (!driver->ttys || !driver->termios) {
3237 if (!(flags & TTY_DRIVER_DYNAMIC_ALLOC)) {
3238 driver->ports = kcalloc(lines, sizeof(*driver->ports),
3240 if (!driver->ports) {
3247 driver->cdevs = kcalloc(cdevs, sizeof(*driver->cdevs), GFP_KERNEL);
3248 if (!driver->cdevs) {
3255 kfree(driver->ports);
3256 kfree(driver->ttys);
3257 kfree(driver->termios);
3258 kfree(driver->cdevs);
3260 return ERR_PTR(err);
3262 EXPORT_SYMBOL(__tty_alloc_driver);
3264 static void destruct_tty_driver(struct kref *kref)
3266 struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
3268 struct ktermios *tp;
3270 if (driver->flags & TTY_DRIVER_INSTALLED) {
3271 for (i = 0; i < driver->num; i++) {
3272 tp = driver->termios[i];
3274 driver->termios[i] = NULL;
3277 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
3278 tty_unregister_device(driver, i);
3280 proc_tty_unregister_driver(driver);
3281 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC)
3282 cdev_del(driver->cdevs[0]);
3284 kfree(driver->cdevs);
3285 kfree(driver->ports);
3286 kfree(driver->termios);
3287 kfree(driver->ttys);
3291 void tty_driver_kref_put(struct tty_driver *driver)
3293 kref_put(&driver->kref, destruct_tty_driver);
3295 EXPORT_SYMBOL(tty_driver_kref_put);
3297 void tty_set_operations(struct tty_driver *driver,
3298 const struct tty_operations *op)
3302 EXPORT_SYMBOL(tty_set_operations);
3304 void put_tty_driver(struct tty_driver *d)
3306 tty_driver_kref_put(d);
3308 EXPORT_SYMBOL(put_tty_driver);
3311 * Called by a tty driver to register itself.
3313 int tty_register_driver(struct tty_driver *driver)
3320 if (!driver->major) {
3321 error = alloc_chrdev_region(&dev, driver->minor_start,
3322 driver->num, driver->name);
3324 driver->major = MAJOR(dev);
3325 driver->minor_start = MINOR(dev);
3328 dev = MKDEV(driver->major, driver->minor_start);
3329 error = register_chrdev_region(dev, driver->num, driver->name);
3334 if (driver->flags & TTY_DRIVER_DYNAMIC_ALLOC) {
3335 error = tty_cdev_add(driver, dev, 0, driver->num);
3337 goto err_unreg_char;
3340 mutex_lock(&tty_mutex);
3341 list_add(&driver->tty_drivers, &tty_drivers);
3342 mutex_unlock(&tty_mutex);
3344 if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
3345 for (i = 0; i < driver->num; i++) {
3346 d = tty_register_device(driver, i, NULL);
3349 goto err_unreg_devs;
3353 proc_tty_register_driver(driver);
3354 driver->flags |= TTY_DRIVER_INSTALLED;
3358 for (i--; i >= 0; i--)
3359 tty_unregister_device(driver, i);
3361 mutex_lock(&tty_mutex);
3362 list_del(&driver->tty_drivers);
3363 mutex_unlock(&tty_mutex);
3366 unregister_chrdev_region(dev, driver->num);
3370 EXPORT_SYMBOL(tty_register_driver);
3373 * Called by a tty driver to unregister itself.
3375 int tty_unregister_driver(struct tty_driver *driver)
3379 if (driver->refcount)
3382 unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
3384 mutex_lock(&tty_mutex);
3385 list_del(&driver->tty_drivers);
3386 mutex_unlock(&tty_mutex);
3390 EXPORT_SYMBOL(tty_unregister_driver);
3392 dev_t tty_devnum(struct tty_struct *tty)
3394 return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
3396 EXPORT_SYMBOL(tty_devnum);
3398 void tty_default_fops(struct file_operations *fops)
3403 static char *tty_devnode(struct device *dev, umode_t *mode)
3407 if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
3408 dev->devt == MKDEV(TTYAUX_MAJOR, 2))
3413 static int __init tty_class_init(void)
3415 tty_class = class_create(THIS_MODULE, "tty");
3416 if (IS_ERR(tty_class))
3417 return PTR_ERR(tty_class);
3418 tty_class->devnode = tty_devnode;
3422 postcore_initcall(tty_class_init);
3424 /* 3/2004 jmc: why do these devices exist? */
3425 static struct cdev tty_cdev, console_cdev;
3427 static ssize_t show_cons_active(struct device *dev,
3428 struct device_attribute *attr, char *buf)
3430 struct console *cs[16];
3436 for_each_console(c) {
3441 if ((c->flags & CON_ENABLED) == 0)
3444 if (i >= ARRAY_SIZE(cs))
3448 int index = cs[i]->index;
3449 struct tty_driver *drv = cs[i]->device(cs[i], &index);
3451 /* don't resolve tty0 as some programs depend on it */
3452 if (drv && (cs[i]->index > 0 || drv->major != TTY_MAJOR))
3453 count += tty_line_name(drv, index, buf + count);
3455 count += sprintf(buf + count, "%s%d",
3456 cs[i]->name, cs[i]->index);
3458 count += sprintf(buf + count, "%c", i ? ' ':'\n');
3464 static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL);
3466 static struct attribute *cons_dev_attrs[] = {
3467 &dev_attr_active.attr,
3471 ATTRIBUTE_GROUPS(cons_dev);
3473 static struct device *consdev;
3475 void console_sysfs_notify(void)
3478 sysfs_notify(&consdev->kobj, NULL, "active");
3482 * Ok, now we can initialize the rest of the tty devices and can count
3483 * on memory allocations, interrupts etc..
3485 int __init tty_init(void)
3488 cdev_init(&tty_cdev, &tty_fops);
3489 if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
3490 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
3491 panic("Couldn't register /dev/tty driver\n");
3492 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");
3494 cdev_init(&console_cdev, &console_fops);
3495 if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
3496 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
3497 panic("Couldn't register /dev/console driver\n");
3498 consdev = device_create_with_groups(tty_class, NULL,
3499 MKDEV(TTYAUX_MAJOR, 1), NULL,
3500 cons_dev_groups, "console");
3501 if (IS_ERR(consdev))
3505 vty_init(&console_fops);